Control arrangement for constant rateyarn delivery carpet tufting machines

ABSTRACT

A control system designed for use in a carpet-tufting machine in which a row of tufts is formed in each cyclical operation of the machine. Each tuft in each row receives yarn from an individual yarn-delivery device, and the control system regulates these devices so that (1) the height of the tufts may be varied both within a row, and from row to row, and (2) the yarns that form the tufts are delivered at a substantially constant rate. The control system starts, advances, and turns off the yarn-delivery devices in accordance with a pre-programmed instruction which identifies the devices to be so operated by group, and number within each group, and thus effects a very rapid operation of the machine.

Unite States Patent [191 Frentress Inventor: Zane Frentress, Greenville,SC.

Deering Milliken Research Corporation, Spartanburg, SC.

Filed: Oct. 1, 1971 Appl. No.: 185,689

Assignee:

US. Cl 112/79 A, 226/9, 226/108 Int. Cl. D05c 15/00 Field of Search112/79 R, 79 A, 266,

ll2/12l.ll, 79; 226/9, 108

References Cited UNITED STATES PATENTS l/1961 Card 226/9 X lO/196OHackney et al 226/9 11/1959 Nowicki 226/9 X [111 grass June 26, 19733,184,798 5/1965 Bumet et al. 226/9 X Primary ExaminerAllen N. KnowlesAttorney-Norman C. Armitage et al.

[57] ABSTRACT A control system designed for use in a carpet-tuftingmachine in which a row of tufts is formed in each cyclical operation ofthe machine. Each tuft in each row receives yarn from an individualyarn-delivery device, and the control system regulates these devices sothat (l the height of the tufts may be varied both within a row, andfrom row to row, and (2) the yarns that form the tufts are delivered ata substantially constant rate. The control system starts, advances, andturns off the yarn-delivery devices in accordance with a preprogrammedinstruction which identifies the devices to be so operated by group, andnumber within each group, and thus effects a very rapid operation of themachine.

16 Claims, 8 Drawing Figures PATENIEDmzs 1915 SEE! 2 0f 5 POSITIONTRANSDUCEQ MOTORS -MGN MOTOR CON 7120i. C/RCUIT5 DECODEF? CORE MEMORYSTA/ID J TAPE //VVE/VTO/? ZANE FRENTRESS TPANS DUCER PATENTEU JUN 26I975 SHEETS 0F 5 DRIVER C/(?.' 76 c BIA/4R) DEC/MAL COA/VfRTfiR FROMCORE 46 STMP CONTROL ARRANGEMENT FOR CONSTANT-RATE-YARN-DELIVERY CARPETTUFTING MACHINES The invention relates generally to control systems forcyclically-operatedmachines which have a large number of outputs thatare to be selectively operated during various cycles of operation andparticularly to such control systems for use in carpet-tufting machines.

There are a great many applications which require control of a largenumber of selected outputs in a cyclically-operated machine, and inwhich the selected outputs may vary from cycle to cycle. An example ofsuch an application is in the metering of yarn in a carpettuftingmachine. Typically, such machines are of a conventional looper-needletype, or of a more recent type which employs pneumatic feed throughhollow needles. In the usual carpet-tufting machine of this type a rowof needles is arranged across a moving web of backing material. Each ofthe needles is hollow and is fed with yarn from a spool. The needles arepushed through the backing material by a needle-bar, and metered lengthsof yarn then are blown through the hollow needles to form loops or tuftsprojecting from the backing material on the side opposite from theneedle-bar. The needles then are withdrawn from the backing, and thebacking material advances a short distance, and the stitching cycle thenis repeated, the needles again being driven into the backing material,and another row of tufts being formed. The height of the tufts isdetermined by the amount of yarn delivered to the needles during eachstitching cycle. More yarn provides a higher loop; less yarn a lowerloop, or no loop at all; if desired. Thus, carpets can be producedhaving a selected height pattern by selectively feeding differentlengths of yarn to the needles to produce the various lengths of loopsdemanded by the selected pattern. Tufting machines of this kind aredescribed in U.S. Pat. No. 3,089,442, of Joe T. Short, entitled TuftingMethod and Apparatus."

In such machines it has been found advantageous to feed the yarn to'eachneedle during each stitching cycle ata constant rate. This constant rateof yarn delivery produces a carpet with an improved appearance, andreduces the possibility of the yarn being broken during the operation ofthe tufting machine. In order to produce a carpet having a variableheight pattern (i.e. tufts of selectively different heights) on aconstant-rate-ofyarn-delivery machine, it is. necessary to control thetime interval during which yarn is delivered to each of the needles ineach stitching cycle. For example, if the constant yarn-delivery rate isone-sixteenth inch of yarn per one one-thousandth of a second (permillisecond), then to produce a loop of one-fourth inch height theyarn-delivery system for that loop must be activated for 8 milliseconds.To produce a loop of twice that height, i.e. one-half inch, theyarn-delivery system must be activated for 16 milliseconds. Machines forproducing this kind of height-patterned carpets are described in U.S.Patent appln. Ser. No. 535,640, now abandoned of Joe T. Short et al.,entitled Controlled Delivery of Yarn, which is assigned to the sameassignee as the present application.

In such carpet-tufting machine, a primary requirement is that theyarn-delivery to each needle function rapidly and reliably because suchmachines must be operated at speeds which produce carpets in commercialquantities, typically 10 to 15 feet a minute. Heretofore, theyarn-delivery controls have been the slowest element in the operation ofsuch a carpet-tufting machine.

A second necessity of such yarn-control systems is reliability of thecontrol circuits, i.e. fault-free operation. Typically, carpet isproduced in 15 foot widths, and the loops or tufts are spaced one-eighthinch from one another; so that 1,440 needles are required to producetufts across the 15 foot width of the carpet. If one of theyarn-delivery controls is malfunctioning, there results down the lengthof the carpet a line of tufts produced by that needle which are eithertoo high or too low. Since carpet is produced in an approximate rate of12% feet a minute, several feet of carpet usually will be producedbefore a flow is detected. After detection, the carpet-tufting machinemust be stopped until the malfunctioning control can be repaired orreplaced. For machines which produce large quantities of carpet at suchhigh speeds, obviously it is important that such down-time be minimized.

Heretofore, circuits have been proposed for controlling the length ofyarn dispensed to each needle (at a constant yarn-delivery rate) duringeach stitching cycle. These prior art circuits included banks of binarycounters, with two counters for each needle. Before each stitchingcycle, a number proportional to the desired height of a tuft was storedin one ofthe two counters. Then, at the beginning of each stitchingcycle, a master clock, providing timed pulses, was started; and yarn wasdelivered at a constant rate to each needle for a period of timedetermined by the number stored in the counter by using these clockpulses to count the counter down to zero, at which time theyarn-delivery system was turned off for the needle associated with thatcounter. Concurrently, another number corresponding to the tuft heightwas stored in the other counter.

The present invention includes a control arrangement for selectivelycontrolling the time during which yarn is delivered to a large number ofneedles in a constant rate-yarn-delivery system. The invention employs anovel system of yarn-delivery control, and of identifying eachyarn-delivery device by group and'by element numbers within that group.At the beginning of a stitching cycle, all of theconstant-rate-yarndelivery devices are activated. Pre-programmedinformation arranged in blocks is stored in an electronic memory. Thefirst block contains the addresses of those yarn-delivery elements whichare to be turned off after a first instant of time, i.e. after a firstamount of yarn is delivered. A second block of information stores thegroup and device numbers of those yarn-delivery elements which are to beturned off after a second instant of time; and so on to the last blockfor the last time interval; which corresponds to the maximum or longestlength of yarn deliverable in one cycle. The reading of thisinformation, block by block, and the resulting turning off of identifiedyarn-delivery devices is synchronized with. the amount of yarndelivered.

By employing pre-programmed information storage arranged in blocks whichcorrespond to steps of the yarn delivery elements, and by using anaddress in which each yarn-delivery device is identified by a group andnumber within the group, it is possible to construct such a controlsystem which is both rapid and reliable. This system employs very fewparts, and this adds to its speed of operation and reliability, as wellas making it less expensive both in cost of materials and assembly.

Another feature of this invention is that it permits the rapidproduction of variable-height-pattern tufted carpet in which the heightpattern may extend for many feet before being repeated, or evenindefinitely if desired. Heretofore machines could manufacture carpetwhose repeat pattern was typically not more than about three feet. Thislength was limited by the mechanical yarn-feeding mechanism. In thisinvention the length of the pattern-repeat is limited only by the numberof preprogrammed instructions supplied to the machine, so that, forexample, it is entirely practical to produce carpet with an 18 footrepeat pattern. Hence, since and 18 foot lengths are typical rug sizes,by using this invention it is possible to producevariable-height-pattern rugs in presently available carpet-tuftingmachines.

It is an object of the present invention to provide a control system fora large number of outputs which are selectively-operated for variousintervals in a control cycle, and whose interval of operation can beselectively varied from cycle to cycle.

It is a further object of the present invention to provide a controlarrangement for a constant-speed-yarndelivery system in which theindividual yarn-delivery elements are selectively operated in each cyclefor different intervals.

Another feature associated with the control arrangement of thisinvention is the format in which the preprogrammed instructions, as toyarn-delivery duration,

are stored. Typically, the instructions for one repeat of the tuftingpattern, for example, one 3 foot length, are stored in a length ofmagnetic tape. Since carpet is made continuously and, therefore, thepatterns are repeated, it is necessary to re-read the instructions onthe tape from the beginning after each pattern is completed. Aftermaking one complete pattern, however, the tape is at the lastinstruction which is at the end of the tape. To repeat the pattern themachine next requires the first instruction which is at the beginning ofthe tape. In accordance with the present invention, in order to obviatethe need to stop and rewind the tape before each repeat, theinstructions for one pattern are interlaced with the instructions forthe next repeat (which, although usually the same as the first, may bedifferent, if desired). By this arrangement the instructions for onepattern are read on the forward movement of the tape, and those for thenext pattern or repeat are read on the reverse movement of the tape.Alternatively, the first half of the total instructions for one patternof a carpet may be interlaced with those of the second half of theinstructions for this pattern. By this arrangement, the first half ofthe instructions are read on the forward movement of the tape; and thesecond half are read on its reverse movement. When an end-ofthe-tapeinstruction at either end is reached, the tape is reversed in direction.Thus, by shuttling the tape (forward and backward), carpets havingrepeated patterns can be produced continuously without the need torewind the tape. A problem arises, however, with tapes using standardIBM format characters. Such tapes, at the end of each record ofinformation (i.e. the instructions for one stitch cycle producing onetransverse row of tufts), there is a stop signal followed by twoparity-check characters. When the tape is read in the forward direction,the parity characters are ignored by turning off the read head. However,when running the tape in reverse direction, the parity characters cannotbe ignored because the read head then is on. The present inventionincludes an arrangement for automatically disregarding the parity-checkcharacters when reading the tape in the reverse direction. Thus itprovides an arrangement permitting the use of a tape with standard IBMformat characters, with two records of instructions interleaved witheach other, one in the forward direction and one in reverse, wherein thestandard IBM parity-check format characters do not affect the reversereading operation.

A still further object of the present invention, therefore, is toprovide an arrangement for reading preprogrammed, interleaved controlinstructions from a standard IBM format tape, and particularly for usein a yarn-delivery control arrangement.

The construction of illustrative embodiments of the present invention,as well as further objects and advantages thereof, will become apparentfrom the following specification when read in conjunction with theaccompanying drawings wherein:

FIG. 1 is a perspective view of a portion of a carpettufting machineusing the control arrangement of this invention;

FIG. 2 is a perspective view of a portion of a single yarn-deliverydevice of the carpet-tufting machine of FIG. 1;

FIG. 3 is a simplified block diagram of a control arrangement of theinvention;

FIG. 4 is a schematic diagram of a single motor, and a block diagram ofthe motor control circuit therefor, adapted for use in the controlarrangement of FIG. 3;

FIG. 5 is a schematic and block diagram of a decoder adapted for use inthe control arrangement of FIG. 3;

FIG. 6 is a block diagram of a portion of the logic circuit of FIG. 3;

FIG. 7 is a schematic diagram of a portion of a control tape, adaptedfor use in the control arrangement of FIG. 3; and

FIG. 8 is a block diagram of a logic circuit used in conjunction withreading the tape of FIG. 7.

Referring now to FIG. 1, there is shown in perspective view a portion ofa carpet-tufting machine, generally indicated at 10. A roll of backingmaterial 11 is mounted near the machine, and this material is fed overguide rollers 12 and 13 to the area where the tufts are inserted in thebacking material. A needle bar 14 extends across the width of thematerial. Individual hollow needles, shown generally at 15, are mountedin the needle bar 14. A typical carpet is 15 feet wide and has tuftsspaced one-eighth inch from each other, or 1,440 tufts across the 15foot width. The machine has one needlefor each tuft, so that there are1,440 needles on the needle bar 14. Each of the needles 15 is providedwith an individual yarn source. The yarnsare mounted on a creel (notshown) and are fed to the tufting machine from above the needle bar in aconventional fashion. The incoming yarns from the creel pass over roller16 through a bank of yarn-delivery elements, shown generally at 18, andthen on to the needles l5. Throughout this description of the invention,examples are given of specific times, dimensions, etc. It should beunderstood that these times and dimensions are exemplary and areincluded as an aid in explaining the invention. They are not limitingsince other times, dimensions, etc. may be used without departing fromthe invention.

The specific example used herein is a hollow needle or honesty typetufting machine, operating to produce tufts on only one side of thebacking material and at a rate of about feet per minute. The inventionis not limited to the honesty type machines, and may be used with thelooper and other types of machines. Further, it is not limited toproducing tufts only on one side of the backing material, since it maybe used to make tufts on both sides of the backing. In the followingdescription of the present invention an output rate of approximately 15feet per minute has been chosen to aid the explanation since with thisrate many of the associated time intervals are whole numbers. Theinvention, of course, is not limited to use at this speed.

A needle-bar movement cycle as used herein means the movement of the barfrom an arbitrary initial position (e.g. its topmost position) throughone complete cycle of motion back to this initial position. In thepresent example the needle-bar cycle lasts for approximately onetwenty-fifth of a second, i.e. 40 milliseconds, so that the needles onthe needle bar pierce the backing material for about 80 percent of thistime, i.e. 32 milliseconds. During each needle-bar cycle yarn isdelivered to the needles, and the maximum time during which yarn can beso delivered will be referred to as the yarn-delivery cycle. Thisyarn-delivery cycle can be as long as, or shorter than, the needle-barcycle, and can begin at any arbitrary time during the needle-bar cycle.In the present example, the yarn-delivery cycle lasts for 32milliseconds, and begins 4 milliseconds after the beginning of theneedle-bar cycle. Thus, when the needles 15 on the bar 14 first piercethe backing material 11, each of the 1,440 yarn-delivery elements in thebank 18 commences to meter the yarn to each needle at a constant rate; Atypical speed of yarn feeding is onesixteenth of an inch permillisecond. At the end of 2 milliseconds, i.e. after one-eighth inch ofyarn is metered out, selected yarn-delivery elements are turned off andno more yarn is delivered to their associated needles. Likewise at theend of 3 milliseconds, 4 milliseconds, and so on, certain yarn-deliveryelements are turned off. While the yarn is being delivered to theneedles, air under pressure blows the yarn through the hollow needles15, thereby forming the yarn into loops on the other side of backingmaterial. The length of each tuft or loop is controlled by the amount ofyarn released by its associated yarn-delivery element, and it isindependent of the pressure of the pressure air forcing the yarn throughthe needles. As the needles are withdrawn from the backing material, itadvances slightly, for example one-eighth of an inch. A take-up reel(not shown) is provided for reeling up the finished tufted material asit leaves the tufting machine. The needlebar and yarn-delivery cyclesthen are repeated. In the present example, the beginning of theyarn-delivery cycle coincides exactly with the beginning of the periodduring which the needles pierce the backing material. It should beappreciated that such coincidence is not essential for proper operationof the machine, nor of the control system of the invention, as theyarn-delivery cycle may be of any convenient duration, and during anyportion, of the needle-bar cycle, and the interval during which theneedles pierce the backing material typically may vary from 80 to 90percent of the needlebar cycle.

Referring now to FIG. 2, there is shown a perspective view of a portionof a single yarn-delivery arrangement for metering yarn to one of theneedles on the needle bar, which arrangement is duplicated for each ofthe 1,440 yarn-delivery elements in the bank 18. The yarn 20 is meteredto a hollow needle 15a in the needle bar 14 from the creel and guideroller (of FIG. 1). It passes between a drive roller 26 and an idlerroller 28, held together by suitable resilient means (not shown), sothat the yarn is gripped between these two rollers. The peripheralsurfaces of the rollers may be provided with a material such as rubber,or plastic, which increases the friction between the yarn and therollers to insure precise metering of the yarn. The drive roller 26 ismounted on the output shaft of a stepping motor (shown schematically at30). When the needles on the bar 14 pierce the backing material, thestepping motor 30 begins stepping (with a clockwise rotation as shown inthis view), thereby drawing yarn 20 from above, and releasing slack yarnto be blown through the needle 15a. The stepping motor 30 advances onestep at a time in synchronism with the pre-programmed control. Each stepof the motor takes approximately 1 millisecond and releasesone-sixteenth inch of yarn. During each yarn-delivery cycle eachstepping motor may be actuated anywhere from as few as two steps to asmany as 32 steps. The first two steps, or 2 milliseconds of operation,are necessary to release the one-eighth inch of yarn which is requiredfor the back stitch, i.e. for the space between adjacent transverse rowsof tufts on the backing material. If it is desired to have a float,i.e., no tuft or loop protruding through the backing, then the steppingmotor is turned off after two steps. If it is desired to produce, forexample, a tuft one-half inch high, the stepping motor makes 18 steps,i.e. two for the back stitch, and 16 to make a loop one-half inch high.The maximum height of a loop in the present example, i.e. one of amaximum of 32 steps, is fifteensixteenths' inch which corresponds tostepping the motor for 32 steps and releasing 2 inches of yarn.

At the end of 32 milliseconds, all of the motors will have been turnedoff, and the needles on bar 14 are withdrawn from the backing material.The feed rolls 12 and 13 are driven by suitable means (not shown) toadvance the backing material past the needle bar, and a correspondingpair of feed rollers (not shown) are employed to move thetuft-containing backing material toward a collection roll (also notshown). This advances the backing material one-eighth inch in the next 8milliseconds, after which time the needles on the bar again pierce thebacking material and the next row of tufts is formed.

Referring now to FIG. 3, there is shown a simplified block diagram ofthe control system of the invention. At the righthand side of thisdiagram there is a block marked Motors 40" which represents the 1,440yarndelivery stepping motors associated with the 1,440 needles. Eachstepping motor in the block 40 is connected to an individual controlcircuit. These circuits are shown, collectively, in a block marked MotorControl Circuits 42. A detail of one such control circuit is shown inFIG. 4 and is described below. As the needle bar 14 moves downwardly andthe needles 15 pierce the backing material 11, a position-sensortransducer (shown schematically at 44 in FIGS. 2 and 3) connected to theneedle bar provides an electric signal indicating that the needles arein a desired position for yarn feed. This signal, designated STMP, isapplied to the motor control circuits 42 and enables the 1,440

motor controls to receive pulses generated elsewhere on the system toactivate the motors. Information as to when the motor controls are to bedisabled (i.e. when the stepping motors are to be turned off) or, putanother way, information as to the number of steps each stepping motoris to take in each cycle, is stored in a magnetic tape shown by block46. The information on the tape is arranged in record. Each recordcontains pre-programmed instructions for a single needle bar movementcycle, i.e. instructions for one transverse row of tufts across thewidth of the backing material. Prior to the beginning of each suchcycle, the record associated with that cycle is transferred from thetape 46 into a core memory 48. This is necessary because the core has afaster read-out time than that of the tape, and this faster read-outtime is required for operation of the tufting machine at commerciallyacceptable speeds. v

The information in each record is arranged in 32 blocks. Each block isassociated with a different step of the stepping motors. The first blockcontrols the first step of the stepping motors. The second block ofinformation contains the addresses of those motors which are to beturned off after two steps of the motor, i.e., after enough thread hasbeen dispensed for the backstitch. (It will be recalled that, in everycycle, the first two steps of the motors meter one-eighth inch of yarnto span the back-stitch space between adjacent rows of tufts, and thatthis 1% inch length of yarn must be provided regardless of whether ornot a tuft is to be formed.) The third block of information contains theaddresses of those motors which are to be turned off after three stepsof the motor (i.e. after a tuft one thirty-secondth inch high) has beenmade; and so on for each additional block.

The information in each block is arranged by group number and motornumber. For example, if it is programmed that the 100th motor will beturned off after the back-stitch, i.e. after two steps of the 100thmotor, then in the second block of information there appears theidentification for the 100th motor. In this example, the motors arearranged in groups of 96 each, and there are 15 groups of motors. Thus,the 100th motor is identified as Group 2, Motor Number 4. After thesecond step of the stepping motors, the third block of information isread out from core 48 to a decoder 50. It has an input for receiving theblock of information, and two sets of output leads, shown schematicallyas 52 and 54. One set 52 of 15 output leads is for Motor Group NumberMGN signals. When a Motor Group Number is received by the decoder 50from the core 48, a signal is provided on one of these 15 MGN outputleads 52; this signal remains on that output lead until the next MGNsignal is received. In the second set of 96 output leads, each leadcorresponds to a different motor number and, when a Motor Number MNsignal is received by the decoder 50 from the core 48, a signal isprovided on one of these output leads 54, corresponding to the motornumber received. The output leads 52 and 54 from decoder 50 areconnected to the motor' control circuits 42.

Each block of information terminates with a block or step groupcomplete(SGC") command which is used for control purposes. This SGCcommand indicates that the block of information has moved from the corememory 48 through the decoding matrix, and that those motor controls,which are to be turned of have been turned off, and that those steppingmotors whose controls are still on may now advance.

The proper timing or synchronization of the various parts of the controlsystem is supervised by a logic circuit 56. The logic circuit 56receives the STMP input signal (which marks the beginning of the yarnfeed cycle) from the transducer 44, and the SGC signal (which marks thecompletion of reading a block of information). The logic circuit 56performs many functions. It (1) supervises the transfer of the recordsfrom the tape 46 to the core memory 48, (2) supervises the transfer ofthe blocks of information from the core memory through the decoder 50 tothe motor control circuits 42, (3) synchronizes the stepping of themotors 40 after each block of information has been decoded, and (4)initiates the reading of the next block of information after thestepping motors have stepped. The command signals from the logic 56 toperform these functions flow through the leads which are shownschematically in FiG. 3 joining it to core memory 48 and through corememory 48 to decoder 50, to tape 46, and to motor control circuits 4 2,and are marked SP, TRC, and SP, respectively. Details of the logic 56are described below in connection with FIG. 6.

Referring now to FIG. 4, there is shown a schematic diagram of a singlemotor 72 and its control circuits 74. There are 1,440 such motors in theblock 40 of FIG. 3, and 1,440 such motor control circuits in the block42 of FIG. 3. The motor 72 is shown schematically as a four-windingstepping motor having windings 72a, 72b, 72c, and 72d. These windingshave two terminals each, one connected to a source of potential, shownhere as +28 volts, and the other connected to an individual drivercircuit, 76a, 76b, 76c, and 7611, respectively, in the control circuit74. When the motor terminal connected to one of these driver circuits isat ground potential, the rotor of the stepping motor 72 rotates to aposition corresponding to that of the winding connected to that circuit;and the rotor then remains locked in that position so long as groundpotential is applied to that winding. By applying ground potentialsequentially to windings 72a, 72b, 72c, and 72d, and then againrepeating their energization in this order, the rotor of the steppingmotor rotates.

The driver circuits 76a, 76b, 76c and 76d are identical, and one ofthese circuits is shown in detail in box 76d. This driver circuit hastwo transistors 78 and 79 whose collectors are connected in commonthrough a diode 81, to a source of potential, shown here as +28 volts.The base of transistor 78 is connected to receive an input signalthrough a lead 82d, its emitter is connected to the base of transistor79, and its collector is connected to the +28 volt source through adiode 81. Transistor 79 has its emitter connected to ground potential,and its collector connected to an output from the driver circuit whichgoes to the motor winding 72d and the +28 volts source through the diode81. A resistor 80 is connected between the base and emitter oftransistor 79. When the driver circuit is not activated, and both thetransistors are off, this resistor maintains the base and emitter oftransistor 79 at the same potential, and thus insures that it remains inthe nonconducting or off condition. Driver circuit 76d is of when aground, or negative potential, is applied at the base of transistor 78through lead 82d. In this condition, transistors 78 and 79 are heldnonconducting because the bases and emitters of each transistor are atthe same potential. Because the motor winding 72d is connected to thecollector of transistor 79, it sees the +28 volts from the potentialsource (through diode 81), and two essentially open circuits at thecollectors of the two non-conducting transistors 78 and 79. Thus, theoutput of the driver circuit 76d is maintained at +28 volts, and themotor winding 72d connected to this driver circuit is not activated.When an input signal of, for example, volts is applied through lead 82dto the input to the driver circuit, i.e., at the base of transistor 78,transistor 78 is switched on or conducting, and is driven intosaturation. This, in turn, produces a potential difference acrossresistor 80 which switches transistor 79 on, rendering it conducting andinto saturation. Thus, saturated transistor 79 essentially has ashort-circuit between its collector and emitter, and the output of thedriver circuit, at the collector of transistor 79, changes essentiallyto ground potential. Current now flows from the +28 source connected tothe motor 72 through the winding 72d, through the collector to emitterof transistor 79, to ground. This current flow advances the steppingmotor 72 to the angular position corresponding to the winding 72d. 80long as transistors 78 and 79 remain conducting, i.e., the drivercircuit remains on, the stepping motor 72 is locked in the position ofthe winding which is activated, here 72d.

Each of the four driver circuits 76a, 76b, 76c, and 76d, are connectedto and are driven by a counter decoder 82. The counter decoder may beany convenient or conventional binary counter decoder of a kind adaptedto receive input pulses on an input lead 83 and sequentially provideoutput signals on four output leads, 82a, 82b, 82c, and 82d. Forexample, if, in response to a first pulse, an output signal appears onoutput lead 82a and activates driver circuit 76a, then, upon receipt ofthe next input pulse, the output signal will be withdrawn from driver76a and an input signal will be provided on output lead 82b, thusactivating driver circuit 76b; and so on for subsequent input pulses,thus providing output signals on the third and then the fourth outputleads 82c and 82d. However, at the fifth input pulse, a signal will beprovided once again on the first output lead, thereby beginning therepetition of the stepping motor energization cycle.

The input to the counter decoder 82 is a train of step pulses" (SP)which are selectively passed to the counter decoder 82 by circuits 88,86, 84 which are controlled by three signals: (1) STMP, the signalproduced at the beginning of a cycle; (2) MGN, the motor group numbersignal; and (3) MN, the motor number signal. The last two signals comefrom the decoder 50. The train of SP pulses are, typically, 1microsecond in duration, and uniformly spaced 1 millisecond apart. TheSP pulses originate in the logic circuit 56, and each pulse (except thefirst in each cycle) is provided only after a complete block ofinformation has been decoded and the step group complete" signal (SGC)has been decoded from the decoder 50. SP pulses are equally spaced intime and are used to'advance the stepping motors. The SP pulses areenabled, or disabled, i.e., passed or blocked, by a circuit made up ofAND gates 88 and 84, and a flip-flop 86. AND gate 84 has two inputterminals and a single output terminal. It has the characteristic thatso long as signals (e.g. +5 volts potential) are applied simultaneouslyat both its inputs, an output signal (e.g. +5 volts) appears at theoutput terminal. For example, should a signal (e.g. +5 volts) appear onthe lower input terminal and an SP pulse (e.g. +5 volts for onemicrosecond duration) appear on the upper input terminal, then pulses of+5 volt amplitude and of one microsecond duration will appear at itsoutput terminal. However, should there be no input signal on the lowerinput terminal of AND gate 84, e.g., zero volts, and should the SP pulsearrive at the upper input terminal, this pulse would be blocked and nosignal would appear at its output terminal.

The lower input terminal to AND gate 84 is connected to an output of aflip-flop 86. This flip-flop 86 may be any convenient or conventionalbinary or bistable multivibrator circuit, of a kind having a pair ofinput terminals, set S and reset R, and an output terminal Q and Q Whena signal is applied at the set input 8, a signal appears and remains onthe set output Q.

When a signal is applied on the reset input R, the signal is withdrawnfrom the set output Q, and a signal appears on reset output 6. (Thereset output 6 of flipflop 86 is shown as not being used in FIG. 4).

T he'set input S of flip-flop 86 is connected to receive the STMPsignal, and it receives a pulse thereon when the needle bar moves towardits down position, and prior to the first block of information beingread out of core memory 48. This sets the flip-flop 86 and produces asignal (e.g. +5 volts) on the set output Q, thus partially enabling ANDgate 84. At the end of the first block of information a step pulse SPappears on the SP lead, which pulse passes through the AND gate 84 toadvance the counter decoder 82 and activate the next driver circuit toadvance the stepping motor 72.

The reset input R of flip-flop 86 is connected to an AND gate 88, whichis of the same operational characteristics as AND gate 84. One input toAND gate 88 is particular motor group number (MGN) lead, while thesecond input is connected to a particular motor number (MN) lead. As anexample, if this circuit shown in FIG. 4 is programmed to be turned offafter the second step, there will appear on the MGN lead and the MN leadto gate 88 after the second SP pulse (i.e. two steps of the motor todispense thread for the back-stitch) but before the third SP pulse, MGNand MN pulses of overlapping duration. When these pulses appearsimultaneously at gate 88, they pass through the gate 88 to the resetterminal R of flip-flop 86, resetting this flip-flop. This, in turnwithdraws the signal from the set output Q of the flip-flop 86, thusdisabling AND gate 84. Subsequently, when a pulse (the third SP pulse inthis stitching cycle) appears on the SP lead to drive those steppingmotors which have not been turned off, it will not drive this motorbecause this stepping motor control circuit 74 has been turned off,"gate 84 being disabled without a signal from flip-flop 86, so that thepulses on the SP lead do not pass through AND gate 84 to operate thismotor 72. Whichever driver circuit 76 previously was activated, remainsactivated, and the stepping motor is locked in that position withcurrent flowing through the winding which was activated last before thecontrol was turned off." Subsequent step pulses appearing on the SP leadare barred from the counter 82 and the driver circuits 76, and thusthere is no further advance of this stepping motor 72 until the nextcycle.

In the next cycle, after the backing material 11 has advanced and theneedle bar 14 has driven the needles l5 downward through the backingmaterial, a new signal appears on the STMP lead, which sets theflip-flop 86, thus partially enabling AND gate 84 to allow step pulsesSP appearing on the SP lead now to pass into the counter decoder 82 andadvance the stepping motor 72. In this next cycle, the motor 72 will bedriven by the SP pulses until the control is turned of by signalsappearing simultaneously on both inputs to AND gate 88 (i.e., on the MGNlead, and the MN lead).

In the example used herein, there are L440 control circuits of the kindshown in FIG. 4. The SP lead is connected to the AND gate 84 in all ofthese l,440 control circuits. The motor group number leads MGN, of whichthere are 15, each are selectively connected to the 96 different controlcircuits, and the motor number leads MN, of which there are 96, each areconnected to 15 different control circuits, namely the Motor Number 1lead (MN-1) is connected to the first motor control circuit to which isconnected the first Motor Group Number lead (MGN-1), the second motornumber lead group (MGN-2), the third motor group number lead (MGN-3),and so forth, to the 15 motor group number lead (MGN-15). The motornumber lead 2 (MN-2) is connected to the second motor control circuit towhich is connected the first motor group numher lead (MGN-l), and to thesecond motor control circuit, to which is connected MGN-2 lead, and soon, until the MN-Z lead to the control circuit to which is connected theMGN-15 lead; and so on up to the 96th lead (MN-96) which is connected tothe 96th motor control circuit of that first group to which is alsoconnected the MGN-1 lead and to the 96th motor control circuit of thatgroup which is also connected to the MGN-2 lead, etc. for the MN-96 leadto the control circuit to which is connected the MGN-l5 lead. Insummary, each of the AND gates 88 in the 1,440 motor control circuitshas a different and unique combination of one MGN input lead (MGN 1through and one MN input lead (MN 1 through 96). By this arrangement,each of the 1,440 motor control circuits can be identified by thecoincidence of a single MN signal plus a single MGN signal.

Referring now to FIG. 5, there is shown a detailed block diagram of thedecoding circuit 50 of FIG. 3. This circuit has an input 90 forreceiving data from the core memory 48, and 15 motor group number MGNoutput leads, MGN-l through MGN-15, and 96 motor number MN output leads,MN-l through MN-96. These leads are connected to the motor controlcircuits 42, as described above. The decoding circuit 50 receivesinformation from the core which is a record" of information, i.e. theinstructions for one complete yarn dispensing cycle. This record is madeup of 32 blocks of information, each block is associated with aparticular step of certain motors, and each block contains the motorgroup numbers MGN and motor numbers MN of those motors which are to beturned off prior to the next step of the stepping motors. Further, eachblock of information (except the last) terminates with a step groupcomplete signal SGC.

The motor group numbers MGN and. motor numbers MN are transferred fromthe core 48 into the decoder 50, one at a time. Each number is binarycoded, as a 7-bit character, which is applied to the decoding circuit 50on seven input leads 90, at the upper left hand side of FIG. 5. Thenumbers from the core 48 arrive sequentially in the following order: amotor group number (MGN) followed by the motor numbers (MN) of thosemotors in that group which are to be deactivated. The decoder includesbinary to decimal convertor 92 of any convenient or conventional designadapted to receive a binary character of at least seven bits and having1 12 output leads, and adapted to provide a signal (e.g. +5 volts) onany one of these 1 12 output leads in accordance with the input binarycharacter, the first 15 output leads corresponding to the motor groupnumbers MGN-1 through MGN-5, and the next 96 output leads correspondingto the motor numbers MN-l through MN-96. The final output leadcorresponds to the stop group complete signal SGC. For example, a motorgroup number 2 code (MGN-2) will produce a signal on the second outputlead from the convertor. A motor number 4 (MN-4) will produce a signalon the MN-4 output lead. Such decoding circuits are conventional andtherefore there is no need to give a detailed explanation of theinternal components and wiring of the decoder 92.

The motor group number MGN signal must be provided at the output of thedecoder 50 for such time as motor number MN signals associated with thatgroup are also being decoded, or until the next motor group number MGNappears lt will be noted that the motor control circuit 74 of FIG. 4 isdisabled upon the simultaneous occurrence of the motor group number MGNand motor number MN associated with that particular motor controlcircuit. Thus, the motor group number MGN signal must be maintainedwhile the motor numbers MN, associated with that group, are beingdecoded. To achieve this end, a latching circuit 94 is connected to thefirst 15 motor group number outputs from the convertor 92; Latchingcircuit inciudes 15 flip-flops, shown here as 96-1, 96-2, 96-3, through96-15. The post-script after the hyphen indicates that the flip-flopsare associated with that motor group. The set terminal S of each of theflip-flops 96-1 through 15 have their set inputs connected to the first15 outputs from the convertor 92, respectively. The set outputs Q of theflip-flops are connected to the motor group nurnber leads MGN-l, MGN-2,through MGN-1S, respectively. The reset input of the first motor groupflipflop 96-1 is connected to the set input S of the second motor groupflip-flop 96-2, and each succeeding flipflop 96-2 through flip-flop96-15 has its reset input R connected to the set input of the next orhigher stage group number flip-flop. The reset terminals R of all theflip-flops 96-1 through 96-15 also are connected to the STMP lead.Diodes 97 are connected between the STMP lead input and the lead fromeach of the next or higher stage group number flip-flops and in the setS to the reset R leads to prevent false triggering. Thus, at thebeginning of a stitching cycle, all of the flip-flops 96-1 through 96-15in the latching circuit 94 are reset. Upon occurrence of the first motorgroup number MGN a signal appears on the set lead 8 of flip-flop 96-1,setting the flip-flop and providing a signal on the MGN-l lead. Anymotor numbers MN immediately following this motor group number MGN aredecoded and a signal is sent out over the appropriate-motor number leadMN-l to MN-96. Upon the reading and decoding of the next motor groupnumber MGN, a signal appears on the second output of the convertor 92.This signal is applied simultaneously to the reset terminal R offlip-flop 96-1 and to the set terminal S of 96-2. This resets flip-flop96-1 withdrawing the signal from the MGN-1 lead, and sets flip-flop96-2, thus providing a signal on the MGN-2 lead. The operation of theconverter 92 and the latching circuit 94 continues in the same fashionfor the remaining 13 motor groups, after which the operation is repeatedfor the next block of information for the next tufting cycle. At the endof each block of information there appears a 7-bit character identifyingthe end of the block, i.e. that the next stepping of the motors now mayproceed. This character is decoded by the converter 92 and provides apulse on the 112th output lead from this converter 92. This lead, andthe signal on it, are called step group complete SGC.

Referring now to FIG. 6, there is shown a block diagram of a portion-ofthe logic and control circuit 56 of FIG. 3. This portion of the logiccircuit provides the step pulse on the SP lead which is applied to theAND gates 84, in 1,440 motor control circuits (FIG. 4), to advance themotors at the properly synchronized instants of time. A signal on the SPlead also is applied to the core memory 48 to initiate the reading ofthe next block of information from the core. The inputs for this portionof the control circuit of FIG. 6 are the STMP signal which marks thebeginning of a yarndispensing cycle, and the step group complete SGCsignal from the decoder 50 which occurs at the end of a block ofinformation.

In FIG. 6 there is shown a one megacycle clock 110 which provides pulsesat a frequency of one megacycle per second-These pulses are applied to acounter 112 which divides the one megacycle pulse train by 1,000 andproduces one pulse at its output for each 1,000 pulses received; thusthe counter 112 produces a pulse on lead 113 once every millisecond.This pulse is the basic timing pulse for synchronizing the advance ofthe counter decoder 82 in the motor control circuit (FIG. 4) whichcauses the stepping motors to advance. The STMP signal also is appliedto the counter 112. This pulse sets the counter in block 112, andsynchronizes the beginning of the step pulses SP produced by the counter112 to occur when the needle bar 14 reaches the position at which yarnfeed is to start. The counter 112 may be any convenient or conventionalcounter circuit of a kind which receives a train of input pulses andprovides a single output pulse after a predetermined number of inputpulses have been received, i.e. 1,000 input pulses in the presentexample.

It will be appreciated that the speed of operation of the steppingmotors is determined by the frequency of the pulses coming from thecounter 112. In the present example, there is one output pulse from thecounter each millisecond. Thus, an elapsed time of 32 milliseconds isrequired to feed the maximum of 32 increments of yarn. If it isdesirable to operate the yarn-feed mechanism at a faster rate, thecounter 112 may be adjusted to produce pulses more rapidly, for example,one every 700 microseconds, or one every 500 microseconds. The latterrate would operate the machine twice as fast as in the embodimentdescribed herein. The speed of the operation also is limited to a largeextent by the time required to transfer the information from the tape tothe core memory. As faster peripheral equipment is used with the systemof the invention, the counter 112 may be adjusted as pointed out aboveto put out one output pulse for every 700 received pulses, or for every500 received pulses. This feature of being able to set the speed of thetufting machine by adjusting the counter setting adds to the versatilityof the overall system of the invention.

The pulses on lead 113 are applied to one of two inputs of an AND gate114. If this gate is partially enabled by a signal from a flip-flop 116on its second input, then the pulse on lead 113 passes through the gate114 to the output SP lead and is applied over the SP lead to the 1,440motor control circuits. The set terminal S of the flip-flop 116 isconnected to the STMP lead through a blocking diode, and also to the SGClead from the decoder 92 which carries the decoded step group completesignal SGC. This step group complete signal SGC is provided at the endof each block of information (each block corresponding to one step ofthe stepping motor). Thus, after the instructions for one step of themotor have been applied from the decoder 50 to the motor controls 42,the step group complete signal SGC is applied from decoder 50 toflip-flop 116 in the logic circuit. This SGC signal sets the flip-flop116 and this, in turn, partially enables AND gate 114. The motor controlcircuits 42 are now ready to receive the step pulses SP to advance thosemotors whose control circuits have not been previously turned off by MNand MGN signals from the decoder 50.

The output pulse on the SP lead is also fed back by a conductor 1 l7(and if needed through a suitable time delay circuit (not shown)) to thereset input terminal R of flip-flop 116; this pulse which resets thisflip-flop also withdraws the output signal from the set output terminalQ of flip-flop 116 and thereby disables AND gate 114. Thus, thesubsequent step pulse SP cannot be applied to the motor control circuitsuntil the next block of information is read out from the core 48,decoded, and the step group complete signal'SGC in that block has beenapplied on lead SGC to set the flip-flop 116.

The last block of information in each record does not end with a stepgroup complete command SGC, but with an end-of-record command. Thus, theflip-flop 116 is not set at the end of the last block and subsequentpulses from the counter 112 are not passed through the AND gate 114. Ofcourse, the motor control circuits identified in this last block aredisabled or turned off, thereby providing a double-check against falsestepping of the motors:-first blocking the SP pulses, second turning offall the motor control circuits.

The system is designed to dispense yarn at a constant rate, e.g. thestepping motors can feed one-sixteenth inch of yarn each millisecond,pursuant tothe one millisecond pulses from the counter 112. It isexpected that almost all those motors which are to be turned off after agiven step of the motors can, in fact, be turned off before the nextstep pulse arrives, i.e. within 1 millisecond period. It has been found,however, that in certain circumstances (e.g. turning off all the motorsafter one step) it is not possible to complete this turning off in theone millisecond period. The logic circuit 56, and particularly flip-flop116, inhibits a subsequent occurring pulse from counter 112 until all ofthe motor controls associated with the last block of information havebeen deactivated. For example, it requires about 1 microsecond to readone character from core, decode it, and deactivate the identified motorcontrol circuits. If all the motors are to be turned off at the end ofone step, the block of information associated with the next stepcontains 15 motor group numbers (MGN) and 1,440 motor numbers (MN) plusone step group complete SGC character. It takes approximately 1.5milliseconds to decode and deactivate the motor controls for this largeblock of information. It is important that the step pulse SP not beapplied to the motor control circuits before all of them aredeactivated. Thus, when a pulse is provided from counter 112 on lead 1131 millisecond after the previous stepping of the motors, it is blockedby AND gate 114, due to flip-flop 1 16 not having been set because nostep group complete signal SGC from decoder 92 was applied to theflip-flop 116. This step group complete SGC signal will occurapproximately 500 microseconds later. Thus, one step pulse SP is skippedand it is the subsequent output pulse from the counter 112 which passesthrough the gate 114. This step, and subsequent steppings of the motors,would be 1 microsecond apart but timedelayed one microsecond from theoriginal starting step pulse SP. This gap in the stepping pulses doesnot significantly affect the constant rate of yarn feed for those motorswhich are still on. As a practical matter, there will be only one extraspace between adjacent pulses in this example, and this occurs only ifmore than approximately two-thirds of the motors are to be turned offafter one step (approximately 980 motors in that step); and this, ofcourse, can only occur once in a tufting cycle. If it is desirable tooperate the tufting machine at faster speeds, such as providing a steppulse every half millisecond, it might be necessary to postpone orinterrupt the equally-spaced pulse periods for as many as two pulses.

The flip-flop 116 performs an additional function. If, in'a record ofinformation, the instructions in the eighth block (i.e. after the eighthstep of the motor) become lost (this is an occasional occurrence incomputers where a portion of a record of information can be lost), thenthe flip-flop 116 will stop all the motors after the eighth step.After'the seventh block of information, a stepgroup complete signal SGCis applied to flip-flop 116 setting the flip-flop. The counter 112provides a step pulse for the eighth stepping of the motors whichadvances those motors which have not yet been turned off, and the steppulse from AND gate 114 also is fed back on lead 117 to resetflip-flop'llfi. The instructions, however, for the ninth through thethirty-second steppings of the motors have been lost from the record.Thus, there is no means for applying a step group complete'SGC signal toset flip-flop 116. Thus, subsequent pulses from counter 112 are blockedby the partially disabled AND gate 114 and those motor control circuitswhich have not been disabled do not advance the stepping motors furtherbecause there are no SP pulses to advance the-counter decoder 82 in themotor control circuits (FIG. 4). Hence, the row of tufts associated witha record having several lost blocks of information appears as a low row,i.e., no higher in this example than three-sixteenths inch high. This isadvantageous in that an erroneous row of low tufts is not readilynoticeable in the finished carpet while an erroneous row of high tuftsis readily noticeable and makes the carpet commercially unusable. Thus,with this circuit, should a portion of a record he lost, the motors aredisabled in the absence of a portion of a record for that missingportion, with the result that the lost portion produces a commerciallyacceptable row of low tufts, rather than an unacceptable row of hightufts.

The first SP pulse which causes the first step of the motors in eachyarn dispensing cycle is initiated by the STMP signal. This permits themotors to begin stepping in each cycle as soon as the STMP pulse isproduced.

The step pulse signal SP and step group complete signal SGC also areused to regulate the transfer of information from the tape to the corememory 48. Typically, the transfer of information from the core 48 tothe decoder 50 is quite rapid, e.g., l microsecond per character. Thetransfer of information from the tape to the core, however, is muchslower, typically 15 microseconds per character. Thus, to read an entirerecord of approximately 1,500 characters from core to decoder takesapproximately 1.5 milliseconds, but to load this record of informationinto the core from the tape takes approximately 22.5 milliseconds.Hence, if a needlebar-movement cycle has a duration of 40 milliseconds,it is necessary to read the information from the tape to the core duringthose time intervals when the information isnot being read from core tothe decoder 50. The core 48 is divided for convenience into twoportions. Information is read out of one portion of the core into thedecoder, while the next record of information is being read from thetape into the other portion of the core. This core memory, however, isof a kind which does not permit the simultaneous reading into the coreand reading out of the core; thus it is necessary to read from the tapeinto the core during those intervals when the information is not beingread out of core. To achieve this, the step group complete SGC and steppulse SP signals are used. The step pulse signal SP from logic 56 notonly advances the motor circuits, but also is applied to the core 48 toinitiate the reading of the next block of information from the core intothe decoder. The step group complete signal SGC from decoder 50indicates that this block of information has been read from the memoryand has been decoded. The step pulse SP occurs at periodic intervals,and there is an increment of time between the step group complete pulseSGC from decoder 50 and the occurrence of the step pulse SP. This timeincrement is used to read a next piece of information from the tape intothe core memory. Particularly, the step group complete signal SGC fromthat portion of the core being used for readout is used to initiate atransfer of information from the tape into that portion of the core thatis not being used for readout. This reading from tape to core continuesuntil the step pulse SP occurs which also is applied to the tape andcore memory and stops the reading from the tape. This is repeated untilthe entire record is read from the tape to memory. Since a stitchingcycle is 40 milliseconds, and since it takes approximately 1%milliseconds to read a record out of core, thereremains approximately38% milliseconds to read from tape to core, certainly sufficient timefor the transfer considering that only approximately 22% millisecondsare needed.

Referring now to FIG. 7, there is shown schematically a portion of amagnetic tape containing the last few instructions of one record and thefirst few instructions of a subsequent record. Carpets produced by thismachine usually have a pattern which repeats along the length of thecarpet, for example, up to every 36 inches. The instructions for onerepeat of such a tufting pattern are stored on a length of magnetictape. Since carpet is made in a continuous strip and since the patternis repeated, it is necessary to reread the instructions on the tape fromthe beginning after each patterned carpet is completed. Normally, aftermaking one pattern repeat in the carpet, the tape is at the lastinstruction which is at the end of the tape. To repeat the pattern, themachine would then require the first instruction which is at thebeginning of the tape. In the present invention, in order to eliminaterewinding of the tape to the first instruction, a second set ofinstructions are interlaced with the first set of the instructions butin a reverse direction, e.g., the instructions for two repeats areinterlaced with each other in reverse directions. Alternatively, asingle set of instructions for a single pattern repeat could be dividedinto two interlaced groups of instructions. This is shown in FIG. 7where the characters to be read in the forward direction are marked witha dark spot in the bottom-most position, and those without this mark areread in the reverse direction. By this arrangement, the first half, orone complete set, of the instructions are read during the forwardmovement of the tape, and the second half, or second complete set, areread during the reverse movement of the tape. When the end of the tapeinstruction at either end is reached, the tape is reversed in directionupon reading a tape reversal instruction character. Thus, by shuttlingthe tape (once forward and once backward) carpets are producedcontinuously, and without rewinding the tape.

With this arrangement a problem arises, however, with the use ofstandard IBM format characters on the tape. At the end of each record ofinformation (i.e., the instructions for one transverse row of tufts)there is a stop character signal (180 in FIG. 7) followed by twoparity-check characters, 182 and 184. In reading of the tape in theforward direction, when a forward-tapestop-command 180 is sensed, thissignal is decoded and the logic receiving data from the tape is switchedoff; the tape drive is then commanded to stop and the tape drive coaststo a stop at a point which is beyond the parity-check characters, 182and 184. Thus, when the tape drive is started again, it begins readingthe next record of information and does not read the parity-checkcharacters. However, when reading in the reverse direction, i.e., fromright to left in FIG. 7, once a reverse direction tape-stop-command isdetected at point 186, the logic receiving data from the tape drive isswitched off. The tape drive then is commanded to stop, and the tapedrive coasts to a point at approximately 188, i.e., before theparity-check characters 182 and 184 are reached. When instructions arereceived from the machine to begin reading from the tape again, thefirst two characters read in the reverse direction are the paritycheckcharacters 182 and 184. These parity-check characters, if entered intothe control system for the tufting machine, would cause an improperoperation of the yarn feeding mechanisms.

This difficulty is overcome by use of the arrangement shown in FIG. 8which is a schematic diagram of a circuit to prevent the parity-checkcharacters from affecting the control system. This arrangement therebypermits the use of standard IBM format tape in which records ofinformation are interleaved to be read in forward and then reversedirections. In the circuit of FIG. 8, information from the read heads isapplied through a lead 200 to a small decoder 202. This decoder issensitive to a tape-stop-command in the forward direction and to atape-stop-command in the reverse direction, and provides an output pulseon a lead 204 in response to decoding a tape-stop-command in the forwarddirection and a pulse on lead 206 in response to decoding atape-stop-command in the reverse direction. A flip-flop 208 has its setinput terminal S and reset input terminal R connected, respectively, toleads 204 and 206 from decoder 202. The set output Q from this flip-flop208 is connected to an AND gate 210. A second input to AND gate 210 is alogic signal instructing that data be received from the tape. Thecircuit of FIG. 8 is effective only when the tape is running in thereverse direction. A third input may be applied to gate 210 to providean output signal only when the tape is moving in the reverse direction.Upon the sensing of a reverse direction tape-stop-command, decoder 202provides a signal on lead 206 which resets flip-flop 208. This withdrawsthe signal from the set output Q of flip-flop 208 and disables AND gate210. When the tape drive is switched on again, a signal to receive datais applied to the second input on lead 212 of the AND gate 210. However,AND gate 210 is disabled due to the absence of a signal on its firstinput lead. As the read head passes over the parity-check characters 182and 184, they are read into the decoder 202, but they are not read intothe logic-receiving data circuit, i.e., the core memory. The nextcharacter sensed is from the forward direction tape-stop-command signal180. This is decoded by decoder 202, which now provides a signal on itsoutput lead 204. This sets the flip-flop 208 and provides a signal onthe set output Q of flip-flop 208, thus qualifying the AND gate 210. Thesignal on lead 212 now passes through the AND gate 210 to the corememory and other logic circuit receiving data from the tape so that theynow will receive the characters of the record which now are being readby the tape head. Thus, by the inclusion of the circuit of FIG. 8, therecords of information may be interleaved so that the tape may be readin the forward and reverse direction while still employing standard IBMformat tape.

Thus, there has been shown and described a control system, which in oneembodiment is applied to a carpet tufting machine in which a pluralityof stepping motors for feeding yarn are rapidly and accuratelycontrolled to deliver the right amount of yarn to each needle duringeach stitching cycle.

Although illustrative embodiments of this invention have been describedin detail herein with reference to the accompanying drawings, it is tobe understood that the invention is not limited to those preciseembodiments, and that various changes and modifications may be effectedtherein by one skilled in the art without departing from the scope orspirit of the invention.

What I claim is:

l. A yarn control arrangement .for a cyclicallyoperated tufting machine,in which, in each cycle of operation, a plurality of yarns of differentlengths are dispensed at a substantially constant rate through a backingto form at least a portion of a row of tufts comprising, in combination,

a. a plurality of stepping means for feeding predetermined lengths ofyarn with each step of said stepping means;

b. means for generating spaced pulses which are adapted to step saidplurality of stepping means;

c. switch means for applying said pulses from said generating means tosaid plurality of stepping means; and

(1. means for storing information in records which are made up of blocksof information, a record being provided for each cycle of operation, andeach of the blocks of a record corresponding to a different step of saidstepping means, said information within each block identifying thosestepping means which are to be switched in connection with the step withwhich the block is associated; said information being arranged toidentify said stepping means by group and number within the group; andsaid switch means including means operatively responsive to theidentification of the stepping means by group and number.

2. A control arrangement according to claim 1 further comprising, incombination,

a. a plurality of hollow tufting needles arranged in a row; to whichyarn is metered in predetermined steps and at a substantially constantrate by the stepping means;

b. a source of fluid pressure for blowing the metered lengths of yarnthrough the needles to make the tufts;

0. means for sequentially recalling from the information storing meansthe blocks of information in synchronism with the steps; and

d. means responsive to each of the recalled blocks of information forselectively controlling the switch means to turn off the stepping meansidentified in each block by group and number before the next step of thestepping means.

3. A yarn control arrangement according to claim '1 in which said switchmeans connect said pulsegenerating means to said plurality of steppingmeans at the beginning of a cycle of operation and disconnect saidpulse-generating means from those stepping means identified in a blockafter that step of the stepping means associated with said block.

4. A yarn control arrangement according to claim 1 wherein said switchmeans connects said pulsegenerating means to said stepping means when astepping means is identified in a block and after the step of thestepping means associated with that block, and said switch meansdisconnects said pulse-generating means from said stepping means at apredetermined interval in the cycle.

5. A control arrangement according to claim 1 including means forsequentially distributing said information blocks in synchronism withsaid steps, and providing group and stepping means number signals to theswitch mea'ns'in accordance with the group and number information in theblock.

6. A control arrangement according to claim 3, further comprising meansfor providing an electrical signal at the beginning of each cycle; andwherein said switch means includes a plurality of gates, each of saidgates being associated with one stepping means, and being connected toreceive said pulses from the pulsegenerating means, and having meansresponsive to a beginning of cycle signal for passing said pulses tosaid associated stepping means, each of said gates also having an inputcorresponding to a group number and a stepping means number, and havingmeans responsive to the receipt of a group and a stepping means numbersignal thereon for barring additional pulses from said pulse-generatingmeans to said stepping means.

7. A control arrangement according to claim 6 wherein each of said gatesincludes a pair of logic gates, one of said logic gates being connectedto receive group and motor number signals, and the other of said logicgates being connected to receive pulses from said pulse-generatingmeans, said other logic gate being enabled by the signal marking thebeginning of a cycle, and being disabled by a signal from said firstlogic gate which receives the group and stepping means number signals.

8. A control arrangement according to claim 7 wherein each of said gatesfurther includes a twocondition flip-flop connected to receive thesignal marking the beginning of a stitching cycle and put in onecondition by said signal, and also being connected to said other logicgate and adapted to be put in its other condition by a signal from saidgate, and an output of said flip-flop being connected to said firstlogic gate to enable such gate when said flip-flop is in the onecondition and to disable the gate when it is in the other condition.

9. A control arrangement according to claim 1 wherein said blocks ofinformation terminate with an end-of-block signal, and means areprovided for inhibiting that pulse to step said stepping means which isassociated with the next block until after said end-ofblock signal isreceived by said inhibiting means.

10. A control arrangement according to claim 9 wherein said inhibitingmeans includes means for blocking the next arriving step pulse if saidend-ofblock signal has not arrived prior to the occurrence of saidpulse.

11. A control arrangement according to claim 9 wherein said means forstoring information includes a fast-access memory and a slow-accessmemory, and wherein means are provided for initiating the transfer fromsaid slow-access memory to the fast-access memory in the intervalbetween the end-of-block signal and the associated pulses to step thestepping means.

12. A control arrangement according to claim 1, wherein means areprovided for synchronizing said pulses from said generating means withthe beginning of each cycle.

13. A control arrangement according to claim 12, wherein means areprovided for varying the frequency of said pulses from said generatingmeans.

14. A control arrangement according to claim 1, wherein said records ofinformation in said means for storing information are arranged ininterleaved pairs with each pair followed by a parity character, each ofsaid pairs of records having at their ends a forwardstop-commandcharacter and a reverse-stop-command character, saidcontrol arrangementfurther comprising readout gate means for passing the records from theinformation-storing means to said disconnecting and connecting means,meansfor identifying said reversestop-command character and saidforward-stopcommand character, means for disabling said readout gatemeans in response to identification of one of said stop-commandcharacters at the end of a record, and means for enabling said readoutgate means in response to identification of a different stop-commandcharacter at the beginning of a next record.

15. A control arrangement according to claim 14 wherein said means fordisabling and enabling is a flipflop having its set and reset inputsconnected to the identifying means, and its output connected tothe gatemeans.

16. A control arrangement according to claim 15 wherein saidstop-command character at the end of a record is thereverse-stop-command character, and the stop-command character at thebeginning of the next record is the forward-stop-character.

i i I. i l

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 9 IDted June 26, 1973 Inventor) Zane Frentress It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

In the specification, column 2, line 15, 10W" should read --flaw--.

Signed and sealed this 6th day of August 1971+.

(SEAL) Attest:

MCCOY M. GIBSON, JR. C. MARSHALL DANN Attesting Officer Commissioner-cfPatents

1. A yarn control arrangement for a cyclically-operated tufting machine,in which, in each cycle of operation, a plurality of yarns of differentlengths are dispensed at a substantially constant rate through a backingto form at least a portion of a row of tufts comprising, in combination,a. a plurality of stepping means for feeding predetermined lengths ofyarn with each step of said stepping means; b. means for generatingspaced pulses which are adapted to step said plurality of steppingmeans; c. switch means for applying said pulses from said generatingmeans to said plurality of stepping means; and d. means for storinginformation in records which are made up of blocks of information, arecord being provided for each cycle of operation, and each of theblocks of a record corresponding to a different step of said steppingmeans, said information within each block identifying those steppingmeans which are to be switched in connection with the step with whichthe block is associated; said information being arranged to identifysaid stepping means by group and number within the group; and saidswitch means including means operatively responsive to theidentification of the stepping means by group and number.
 2. A controlarrangement according to claim 1 further comprising, in combination, a.a plurality of hollow tufting needles arranged in a row; to which yarnis metered in predetermined steps and at a substantially constant rateby the stepping means; b. a source of fluid pressure for blowing themetered lengths of yarn through the needles to make the tufts; c. meansfor sequentially recalling from the information storing means the blocksof information in synchronism with the steps; and d. means responsive toeach of the recalled blocks of information for selectively controllingthe switch means to turn off the stepping means identified in each blockby group and number before the next step of the stepping means.
 3. Ayarn control arrangement according to claim 1 in which said switch meansconnect said pulse-generating means to said pluraLity of stepping meansat the beginning of a cycle of operation and disconnect saidpulse-generating means from those stepping means identified in a blockafter that step of the stepping means associated with said block.
 4. Ayarn control arrangement according to claim 1 wherein said switch meansconnects said pulse-generating means to said stepping means when astepping means is identified in a block and after the step of thestepping means associated with that block, and said switch meansdisconnects said pulse-generating means from said stepping means at apredetermined interval in the cycle.
 5. A control arrangement accordingto claim 1 including means for sequentially distributing saidinformation blocks in synchronism with said steps, and providing groupand stepping means number signals to the switch means in accordance withthe group and number information in the block.
 6. A control arrangementaccording to claim 3, further comprising means for providing anelectrical signal at the beginning of each cycle; and wherein saidswitch means includes a plurality of gates, each of said gates beingassociated with one stepping means, and being connected to receive saidpulses from the pulse-generating means, and having means responsive to abeginning of cycle signal for passing said pulses to said associatedstepping means, each of said gates also having an input corresponding toa group number and a stepping means number, and having means responsiveto the receipt of a group and a stepping means number signal thereon forbarring additional pulses from said pulse-generating means to saidstepping means.
 7. A control arrangement according to claim 6 whereineach of said gates includes a pair of logic gates, one of said logicgates being connected to receive group and motor number signals, and theother of said logic gates being connected to receive pulses from saidpulse-generating means, said other logic gate being enabled by thesignal marking the beginning of a cycle, and being disabled by a signalfrom said first logic gate which receives the group and stepping meansnumber signals.
 8. A control arrangement according to claim 7 whereineach of said gates further includes a two-condition flip-flop connectedto receive the signal marking the beginning of a stitching cycle and putin one condition by said signal, and also being connected to said otherlogic gate and adapted to be put in its other condition by a signal fromsaid gate, and an output of said flip-flop being connected to said firstlogic gate to enable such gate when said flip-flop is in the onecondition and to disable the gate when it is in the other condition. 9.A control arrangement according to claim 1 wherein said blocks ofinformation terminate with an end-of-block signal, and means areprovided for inhibiting that pulse to step said stepping means which isassociated with the next block until after said end-of-block signal isreceived by said inhibiting means.
 10. A control arrangement accordingto claim 9 wherein said inhibiting means includes means for blocking thenext arriving step pulse if said end-of-block signal has not arrivedprior to the occurrence of said pulse.
 11. A control arrangementaccording to claim 9 wherein said means for storing information includesa fast-access memory and a slow-access memory, and wherein means areprovided for initiating the transfer from said slow-access memory to thefast-access memory in the interval between the end-of-block signal andthe associated pulses to step the stepping means.
 12. A controlarrangement according to claim 1, wherein means are provided forsynchronizing said pulses from said generating means with the beginningof each cycle.
 13. A control arrangement according to claim 12, whereinmeans are provided for varying the frequency of said pulses from saidgenerating means.
 14. A control arrangement according to claim 1,wherein said records of information in said means for storinginformation are arranged in inTerleaved pairs with each pair followed bya parity character, each of said pairs of records having at their ends aforward-stop-command character and a reverse-stop-command character,said control arrangement further comprising readout gate means forpassing the records from the information-storing means to saiddisconnecting and connecting means, means for identifying saidreverse-stop-command character and said forward-stop-command character,means for disabling said readout gate means in response toidentification of one of said stop-command characters at the end of arecord, and means for enabling said readout gate means in response toidentification of a different stop-command character at the beginning ofa next record.
 15. A control arrangement according to claim 14 whereinsaid means for disabling and enabling is a flip-flop having its set andreset inputs connected to the identifying means, and its outputconnected to the gate means.
 16. A control arrangement according toclaim 15 wherein said stop-command character at the end of a record isthe reverse-stop-command character, and the stop-command character atthe beginning of the next record is the forward-stop-character.